Productivity Back in Focus for 200mm Fabs

By David Lammers

There was a period, one that ended five or more years ago, when the semiconductor equipment industry put nearly all of its attention into improving 300mm manufacturing. Jon Farr, an Applied Materials applications technologist, summed it up: "The industry largely stopped working [on 200mm], the technology stagnated, and equipment companies mainly refurbished tools and sold them with a Tier 2 spec."[1]

Then smartphone sales exploded. Analog, MEMS, CMOS image sensors, and power ICs went to high volumes, mainly at 200mm fabs. Within a short time, not only had unit volumes become much higher, technologies had advanced. For power ICs and some MEMS sensors, for example, films became much thicker, outpacing the capabilities of legacy chambers.

"The productivity of original 200mm systems was challenged," said John Cummings, managing director of marketing and business development for Applied Global Services (AGS).

Applied Materials did a rethink. Rather than focus development solely on 300mm tools, the company put more resources into redesigning 200mm chambers, developing bridge tools that can handle both 300mm and 200mm wafers, reinventing important subsystems, replacing the aging system controller with the new Applied Vita controller, and integrating new automation software and service options.

AGS engineers reconsidered the 200mm epi chamber, adapting it to handle much thicker films. Today, Applied’s new high-growth-rate (HGR) epi chamber has twice the deposition rate of a standard chamber, running at 6 microns a minute—double that of the older chamber. The new modified process kit not only doubled the growth rate, it met a tighter flatness specification as well.

Cummings said the HGR epi chamber delivers an overall productivity improvement of more than 10%, although under some special conditions the improvement could be up to 100%. "The thicker the film, the greater the improvement."

HGR epi chamber growth rate is ~25% higher than standard epi with the same TCS flow.

Thick Aluminum

Thermal management and deposition rates were challenges for new thick aluminum applications, especially those for high power, Cummings said. "Today we offer a new PVD chamber for thick aluminum that deposits aluminum twice as fast as the standard aluminum PVD chamber."

The new chamber has improved thermal management for thick aluminum and a much higher deposition rate, which is especially needed for high-power applications. "Now we can do in one chamber what competitors do in two," Cummings said.

Next-generation pDC/RF 200mm PVD

Next-generation 200mm/300mm DRIE

Bigger Sweet Spot

In advanced etch applications, such as MEMS gyroscopes, Applied engineers determined that using 300mm chambers for 200mm applications delivered the best results.

Farr said Applied has started to productize MEMS etch chambers using its 300mm etch platforms in a 200mm configuration. "Not only does that make financial sense for companies seeking a path from 200mm to 300mm wafers—these chambers can be configured for 200mm and modified later to work for 300mm wafers—and they use the latest technologies available." He added that for a variety of such bridge reactors, "the learning that has gone into the 300mm chambers has been adapted to 200mm to enhance productivity."

Mike Rosa, head of Marketing for the AGS 200mm Equipment Products Group, noted that for MEMS gyroscopes the spec for the etch sidewall profile tilt has gone from 90 degrees ±.5 degrees to ±.2 degrees.

"To meet that morphological post-etch feature specification, a larger chamber brings advantages," Rosa said. "The plasma that is generated in the chamber is generally more uniform in the center and uniformity can become worse radially. In the case of a 200mm wafer in a chamber originally designed for a 300mm wafer, a larger percentage of the wafer is sitting within the sweet spot, boosting yields."

John Cummings,Managing Director,Marketing and Business Development, AGS

Mike Rosa,Head of 200mm Equipment Marketing, AGS

Carlos Caballero,Front-end Product Line Manager, AGS

"Applied’s approach has advantages in terms of chamber productivity and etch-rate," Rosa said. Applied’s etch systems often run product wafers consecutively, while DRIE systems from other vendors can require that a plasma clean process be run after each deep silicon etch wafer. "When etch rate plus cleaning times are considered in total, the pendulum swings in Applied’s favor," he said.

Vita Controller Cuts Downtime

Carlos Caballero, front-end product line manager at AGS, said for rapid thermal processing (RTP) and epi, the new chambers have much better performance, improving yields, which in itself has an impact on productivity. "When it comes to reducing equipment downtime, the new Applied Vita controller is the best way to minimize corrective maintenance," he said.

The vast majority of existing 200mm tools from Applied Materials are controlled by older technology: a Motorola 68040-based processor running Bob’s Operating System Software (BOSS). "When these controllers crash, as they often do, it may take several hours to reboot and get the tool running properly again. Vita controllers simply don’t crash like the older controllers. Just reducing the time to reboot helps fabs improve their productivity," Caballero said.

Cummings noted that all Applied Materials refurbished tools now go out the door with Applied Vita controllers on board, and existing 200mm customers can also install them on their existing tools—with or without a service agreement.

"The Vita controller opens up so many ways for customers to improve throughput and productivity. And it is essential for customers who seek to employ FDC (fault detection and control) and APC (advanced process control) software. Vita-controlled systems have a 1,000-times faster processing rate and can run the most advanced APC software," he said.

Vita-Enabled Data Modeling

Florent Ducrot, senior marketing director for the AGS services operation, said fab managers often call on Applied’s FabVantage consultants to determine how to reduce "white space" delays in processing steps. When the Vita controller is installed and more modern software is enabled, the consultants and customer engineers can "focus on white space improvements."

Ducrot said once the Vita controllers are in place, the FabVantage experts seek to use the controller-generated data to employ uni-variant (UVA) and multi-variant (MVA) data modeling.

"We spend time with the customer to examine their PM practices and failure rates, then analyze the data to determine where they rank in a best-in-class benchmark."

Armed with that analysis, Ducrot said the Applied FabVantage team can collaborate with the customer "to achieve a committed productivity improvement based on mutually agreed goals, within the framework of a service agreement."

Applied Vita controllers can increase customers’ productivity up to 15%.

CoO Still Matters

Rosa said companies that are supplying the extremely high-volume devices driving the wireless mobility revolution are more receptive to the advancements being offered for legacy tools. But they are also looking much more closely at cost-of-ownership (CoO) issues.

"CoO has always been important to customers, but now it is a really big deal," he said. "For example, with our thick aluminum deposition rollout, it was all about the CoO. So we reengineered our entire chamber to do in one chamber what took two chambers for other suppliers. That’s the kind of cost efficiency that customers demand."

"For power device customers, thicker epi films are a must. Finding a solution that was both affordable and production worthy meant redesigning the motorized lift and streamlining cleaning cycles in the HGR epi chamber so it can be reassembled and aligned much faster," Rosa said.

"Each customer’s path to higher productivity is different," he added. "Productivity means different things to different people. We believe we have upgrades to address each customer’s requirements. And because they are all unique, it is a continuous process."